Fr.: physique solaire
The branch of astrophysics concerned with the study of the physical properties of the Sun based on the most detailed observations which can be obtained for a star.
Fr.: phénomènes solaires-terrestres
Any of the various phenomena observable on the Earth that are caused by the influence of the Sun, such as aurora borealis.
solid state physics
fizik-e estât-e dafzé, ~ hâlat-e jâmed
Fr.: physique de l'état solide
The branch of condensed matter physics concerned with the study of rigid matter or solids in terms of their constituent particles (electrons and nuclei). The bulk of solid-state physics theory and research is focused on the electromagnetic, thermodynamic, and structural properties of crystalline solids.
Fr.: hémisphère sud
Spectro-Polarimetric High-contrast Exoplanet (SPHERE)
Fr.: Spectro-Polarimetric High-contrast Exoplanet (SPHERE)
The → extreme adaptive optics system and → coronagraphic facility at the → European Southern Observatory (ESO) → Very Large Telescope (VLT) (UT3) available from May 2014. Its primary science goal is imaging, low-resolution spectroscopic, and polarimetric characterization of → exoplanetary system at → visible and → near-infrared wavelengths (0.5-2.32 μm). SPHERE is capable of obtaining → diffraction-limited images at 0''.02 to 0''.08 resolution depending on the wavelength. Its → spectral resolution is 30 to 350, depending on the mode.
An instrument that disperses the light into spectral lines and records them.
An instrument for recording monochromatic images of the Sun.
An instrument designed to measure the intensity of a particular spectral line or a series of spectral lines.
Of or relating to → spectrophotometry.
In astronomy, measurement of the absolute fluxes of the components of different frequencies in the spectrum of a light source.
koré (#), sepehr (#)
A solid geometric figure generated by the revolution of a semicircle about its diameter; equation: x2 + y2 + z2 = r2.
M.E. spere, from O.Fr. espere, from L. sphæra "globe, ball, celestial sphere," from Gk. sphaira "globe, ball," of unknown origin.
Koré, loan from Ar. kurat.
sphere of influence
Fr.: sphère d'influence
The region of space around one of the bodies in a system of two celestial bodies where a third body of much smaller mass is influenced by the gravitational field of that body. The sphere of influence of a planet with respect to the Sun has a radius given by: R = RP(MP/MS)2/3, where RP is the radius of the planet's orbit around the Sun, MP is the mass of the planet, and MS is the solar mass. The sphere of influence of the Earth has a radius of about 927,000 km or slightly under 150 Earth radii. Beyond this limit, a space probe will come under the influence of the Sun.
spheres of Eudoxus
Fr.: sphères d'Eudoxe
A series of spheres with varying radii centred on the Earth, each rotating uniformly about an axis fixed with respect to the surface of the next larger sphere, all comprising a model in Greek astronomy to describe the motions of the heavenly bodies. The spheres turned with different speeds about axes with different orientations. The fixed stars revolved around the Earth by the motion of the most distant sphere to which the stars were thought to be attached. Each of the five planets' (Mercury, Venus, Mars, Jupiter, and Saturn) motion could be described using four spheres. The Sun and the Moon required three spheres each to explain their motions. Therefore, a total of 27 spheres described the behavior of the heavenly bodies in terms of circular motion. Eudoxus was the first person to devise a model that could explain the → retrograde motion of the planets in the sky along a looped curve known as the → hippopede.
→ sphere; Eudoxus (Ευδοξοσ) of Cnidus (c 408 BC - c 355 BC), Greek astronomer and mathematician.
Having the form of a sphere; of or pertaining to a sphere or spheres.
Fr.: aberration sphérique, ~ de sphéricité
An aberration of a spherical lens or spherical mirror in which light rays converge not to a single point but to a series of points with different distances from the lens or mirror. Spherical aberration is corrected by using parabolic reflecting and refracting surface.
Fr.: angle sphérique
An angle formed on the surface of a sphere by the intersection of two great circles of the sphere.
ostorlâb-e sepehri, ~ kore-yi
Fr.: astrolabe sphérique
A type of → astrolabe in which the observer's horizon is drawn on the surface of a globe, mounted with a freely rotating spherical lattice work or 'spider' representing the celestial sphere. The earliest description of the spherical astrolabe dates back to the Iranian astronomer Nayrizi (865-922).
Fr.: astronomie sphérique
The branch of astronomy that is concerned with determining the apparent positions and motions of celestial bodies on the celestial sphere. Same as → positional astronomy.
Fr.: coordonnées sphériques
A coordinate system using an origin (O) and three perpendicular axes (Ox, Oy, Oz), in which the position of a point (P) is given by three numbers (r, θ, φ). The coordinate r is the distance from the origin, θ the angle between the z-axis and the r direction, and φ the angle between the projection of r on the xy-plane and the Ox-axis. The coordinate φ is also called the → azimuthal angle.
fozuni-ye sepehri, ~ kore-yi
Fr.: excès sphérique
The difference between the sum of the three angles of a → spherical triangle and 180° (π radians).